1. Field of the Invention
This invention relates to an improvement in a light beam scanning type recording system which records data on a recording material in a dot pattern by raster scanning of a light beam as of a laser, and more particularly to a device for correcting displacement of fixed information such as a form of tables, titles, etc. from data information to be entered in the form by automatically correcting the relative position of a form slide with respect to a linear encoder.
2. Description of the Prior Art
A light scanning type recording system which records data on a recording material is used, for instance, in a laser COM (computer output microfilmer) which records a computer output data on a microfilm. In the laser COM is used a laser beam as a light beam for recording data on the microfilm. Two laser beams of different wavelength, one for read-out and the other for recording, are used in combination. After the two laser beams have been composed into a single light beam, the light beam is deflected by a two-dimensionally deflecting system. A part of the read-out laser beam is used for scanning a form slide carrying form information as of characters and frame lines of a table to provide a form signal, and another part of the read-out laser beam is used for scanning a linear encoder to provide photoelectric pulse signals for making a video clock signal for data read-out and recording. By use of the video clock signal the computer output data are read out and combined with the form signal obtained from the form slide, and the video signal thus obtained is used for modulating the recording laser beam for recording the computer output data combined with the form on a recording material such as a microfilm.
As described above, a video clock signal is generated on basis of the raster scanning of a linear encoder, and the data information is read out by use of the video clock signal. On the other hand, the form slide is raster scanned to provide a form information signal. Then, the data information and the form information are combined together for recording the desired information on a recording material.
Thus, the form information and the data information are outputed independently of each other. Therefore, when the form slide and the linear encoder are not set at the correct positions, the form information and the data information are not combined correctly, and the data may be for instance recorded right on the frame lines and becomes illegible.
In general, in case that the form slide is of the fixed type, the relative position of the form slide with respect to the linear encoder is adjusted at the time of manufacture of the system, and accordingly there is no fear of causing the above mentioned errors in the recording process.
On the other hand, in case that the form slide is of interchangeable type in which, for instance, a number of form slides are retained in a cassette and a desired one of the form slides is automatically selected and set at the recording position, there is a possibility that the form slide is not accurately set at the correct position and the form slide is not correctly combined with the data information on the recording material. In more detail, the form slide which is normally clamped by a clamp and pushed into a recording station along a guide rail or the like is sometimes not pushed into a predetermined correct position in the recording station. In such a case, the form information obtained from the form slide cannot be correctly combined with the data information.